The present invention relates to a silicon solar cell, and to a method for producing such a solar cell.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
A silicon solar cell includes an n-doped and p-doped silicon layer. If photons impinge on a side of the solar cell acting as emitter, charge balancing or a current flow between the two layers occurs, which can be conducted away via contacts. A contact strip composed of metal having many contact fingers is usually applied on the top side of such a solar cell, whereas a continuous metal layer is present as contact on the underside. The contact strip and the metal area form the electrical poles of the solar cell.
A contact strip and metal fingers have hitherto been formed by means of a silver paste, which are applied to the surface in a printing method. One disadvantage here is that the electrical leads formed from the silver paste have a relatively high conduction resistance since the silver paste is structured in porous fashion. Moreover, the contact resistance between the silver paste and the silicon layer arranged underneath is relatively high and the adhesion to the substrate is relatively poor.
To increase efficiency of solar cells, it has been proposed for example to provide a smaller thickness of the emitter layer. As the thickness of the emitter layer is only a few hundred nanometers, the approach to make them even thinner is problematic because the metallic electrical leads can penetrate through such a thin emitter layer, with the result that such a solar cell is electrically short-circuited.
It would therefore be desirable and advantageous to provide an improved solar cell to obviate prior art shortcomings.